High energy compact permanent magnet assembly for loud speakers



May 10, 1966 w. L. ROLLINS 3,250,362

HIGH ENERGY COMPACT PERMANENT MAGNET ASSEMBLY FOR LOUD SPEAKERS Filed April 22, 1963 2 Sheets-Sheet l I: I I6 40 I {k FIG. I l3" H|| E INVENTOR WILLIAM L. ROLLI NS Q. my

ATTORNEY May 10, 1966 w. 1.. ROLLINS HIGH ENERGY COMPACT PERMANENT MAGNET ASSEMBLY FOR LOUD SPEAKERS 2 SheetsSheet 2 Filed April 22, 1963 ATTORNEY United States Patent 3,250,862 HIGH ENERGY CGMPAQT PERMANENT MAGNET ASSEMBLY FUR LGUD SPEAKERS William L. Rollins, Highway 69 5., Monroe, Wis. Filed Apr. 22, 1%3, Ser. No. 274,751 7 (Ilairns. (Cl. 179115.5)

This invention relates to a relatively comp-act permanent magnet assembly for use in loud speakers wherein a stronger magnetic field may be provided in the same space as heretofore utilized or wherein the same magnetic field may be provided by means occupying less space and having less weight than heretofore utilized. More particularly, the invention relates to a cup type permanent magnet assembly.

Permanent magnet assemblies for loud speakers normally comprise a permanent magnet and means associated therewith to concentrate the flux of the magnet in a cylindrically annular space within which is received a voice coil mounted on a voice coil support tube which is attached to the diaphragm of the speaker. Changes in the current flowing through the voice coil interact with a magnetic flux field concentrated in said space to cause the voice coil support tube to move and transmit such motion to the diaphragm to thereby reproduce as sound waves the electrical signals supplied to the voice coil.

Permanent magnet means and the means associated with the magnets to concentrate the flux in cylindrically annular spaces have been relatively complex, have required a relatively great weight of material, have required a relatively large number of operations to make the parts and a relatively large number of operations to assemble the parts and have occupied a relatively great amount of space. In some such assemblies, especially those of the cup type, it has been necessary to provide substantially cylindrical permanent magnetsof relatively brittle material which have a hole extending through the center of the cylinder. It has been expensive to provide such a hole, and the presence of the hole has caused the magnet to occupy more space than a magnet which would provide the same flux and which does not have such a hole, and has caused the assembly associated with the magnet to be relatively larger and more complex. These disadvantages are obviated or mitigated by the assembly of the assembly of the present invention.

It is an object of the invention to provide a relatively compact permanent magnet and associated flux concentrating and supporting assembly, for use in aloud speaker.

Another object is to provide a permanent magnet and associated supporting means and flux concentrating assemly wherein no hole is provided in the magnet.

Another object is to provide a permanent magnet and associated flux concentrating and supporting assembly for use in loud speakers which comprises 'less parts, occupies less space, and requires less assembly operations than needed heretofore for such devices.

Another object is to provide a permanent magnet and associated flux concentrating and supporting assembly, for use in loud speakers, which comprises only three parts.

Another object is to provide a permanent magnet and associated flux concentrating and supporting members which, when occupying the same space as previous such assemblies, provide higher flux density in an annular voice coil receiving space than heretofore could be provided without changing the material of the magnet.

Other objects will become apparent from the drawings and from the following detailed description in which it is intended to illustrate the applicability of the invention without thereby limiting its scope to less than that of all equivalents which will be apparent to one skilled in the art. In the drawings like reference numerals refer to like parts and:

FIGURE 1 is a cross-sectional partially fragmentary view of a loud speaker provided with a preferred embodiment of the invention on the back of the loud speaker;

FIGURE 2 is a cross-sectional partially fragmentary view of a modification of the embodiment of FIGURE 1,

wherein the permanent magnet and associated flux concentrating and supporting assembly is in front of the diaphragm or invertedly disposed above the diaphragm;

FIGURE 3 is a cross-sectional perspective view of the pole piece provided in the embodiments of FIGURE& 1 and 2; I

FIGURE 4 is a cross-sectional perspective view of a modification of the embodiment of FIGURE 3;

FIGURE 5 is a cross-sectional perspective view of the magnet of the embodiments of FIGURES 1 and 2;

FIGURE 6 is a cross-sectional perspective view of a preferred embodiment of the cup piece as shown in the embodiments of FIGURES 1 and 2;

FIGURE 7 is a cross-sectional view of a modification of the embodiment of FIGURE 6 FIGURE 8 is a cross-sectional perspective view of a rigid supporting member provided in the embodiment of FIGURE 2.

Referring now to FIGURES 1 and 2, frame member 1, which may comprise one piece as shown or may comprise several pieces, is usually referred to as a basket and is usually made-of metal but may be madeof any other suitable material; it is provided with .an outer peripheral portion or periphery 2 and a hole at the center having periphery 3, or 3'. Diaphragm 5 may be attached at its outer periphery 6 to the peripheral portion 2 of basket 1 by any suitable means, usually adhesive 7. Gasket 8 may be provided, if desired. Diaphragm '5 is provided at or near its center with a hole having periphery 10 to which there may be attached one end of cylindrical voice tube support coil 11 or 11' usually by means of adhesive such as adhesive 12. Extending around voice coil support tube 11 is voice coil 13 or 13 attached thereto by any suitable means such as adhesive (not shown).

To prevent undesirable tilting or lateral shifts in the voice coil, there is provided annular flexible supporting member 15 which may be attached at its outer peripheral edge 16 to basket 1 by any suitable means such as adhesive 17 and which may be attached at its inner periphery 18 to periphery 10 of the diaphragm by any suitable means such as adhesive 12. In FIGURE 1, voice coil 11 extends downward, back of diaphragm 5 through the hole having periphery 3'. In FIGURE 2 voice .coil support tube 11 extends upward or forwardly from diaphragm 5.

The hereinbefore described structure is believed .to be conventional.

In accordance with the invention, there is provided in combination with the hereinbefore described structure, permanent magnet and associated flux concentrating and supporting assembly indicated generally as 20 in FIGURE 1 and 20 in FIGURE 2.

Said assembly comprises three parts: Magnet 25, cup piece 30 and pole piece 50, these parts being also shown in FIGURES 5, 6 and 3 respectively.

Magnet 25 is prefer-ably cylindrical with flat ends and preferably has no holes or grooves therein. Its ends are preferably fiat, parallel and normal to the axis of the cylinder. The cylindrical surface is preferably cast to a close tolerance or ground to a close tolerance by centerless grinding or other suitable method. The material of magnet 25 is usually a relatively brittle ceramiclike material comprising an alloy of cobalt, silica or the like, which can be magnetized to provide a relatively high and relatively permanent magnetic flux.

Cup piece 30 and pole piece 50 are preferably made of a relatively highly permeable magnetic material such as soft iron or other suitable ferrousalloy. Cup piece 30 has a bottom 31 which may be in contact with one end of the magnet and side portion 32 is partially spaced away from the magnet.

The modification of FIGURE 6 which is shown in FIGURE 7, indicated as 30, also has bottom portlon 31 and side portion 32.

The upper surface 33 (33 in FIGURE 7) is in abutting contact with one end of the magnet 25 to position the magnet so that its axis is parallel with the axis of cup piece 30 or 30'. An interior cylindrical surface 34 may be provided extending downward from the periphery of bottom surface 33 and thence outwardly and thence upwardly to provide a first interior cylindrical wall surface portion 35 or 35' which is in interfering or press fitted engagement with the outside of the magnet near its bottom end. Such press fitted or interfering engagement causes the magnet and the cup piece to be held together tightly. The recess provided by wall 34 which extends downwardly and thence outwardly provides a reservoir to receive pieces of metal which may be forced thereinto when the magnet and cup piece are forcibly brought into interfering or press fitted engagement. Such press fitted or interfering engagement is accomplished by providingan outside diameter for the magnet which is from .001 inch to .006 inch greater than the diameter of surface 35.

A second or upper interior cylindrical wall surface I portion 36 or 36' is spaced away from the outside of the magnet throughout its height and circumference and terminates at upper edge surface 37 or 377. The principal exterior wall surface 38 of the'cup piece of FIG- URE 6 may be cylindrical, as shown, or as shown in FIGURE 7 at 38' may be cylindrical, hexagonal, square, or the like, since the cup piece may be machined from bar stock having a polygonal cross-section.

Extending downwardly from the outer periphery of surface 37 and thus located at the top outer peripheral edge of side portion 32 or 32 there is provided a surface 39 or 39', which is preferably cylindrical but may be polygonal, which mates with periphery 3 or 3' of basket 1 so that cup piece may be attached to basket 1 in the embodiment of FIGURE 1 by staking as shown at 40. Extending outwardly from the bottom edge of surface 39 and inwardly from the top edge of 38 is a flat surface 41 adapted to serve as a shoulder to abuttingly engage the bottom of basket 1 in the embodiment of FIGURE 1 to cause assembly 20 to be disposed substantially coaxially with respect to voice tube 11'.

Cup piece 30 or 30 may have bottom 42 or 42' which may be flat as shown, if desired. Bottom 31 may be provided, if desired, with hole 43 extending therethrough.

Referring now especially to FIGURES 3 and 4, pole piece 50 or 50' is generally cup shaped. It has a bottom 'which has an upper surface 56 or 56 and a lower surface 51 or 51' which is an interior bottom surface extending laterally to a periphery. It is in abutting contact with one end of magnet 25 to cause the axis of the pole piece to be parallel to the axis of the magnet. An interior cylindrical wall surface 52 may be provided extending upwardly from said periphery, thence outwardly and thence downwardly to provide an interior cylindrical wall surface 53. In the embodiment of FIGURE 4 a comparable interior cylindrical wall surface 53' may be provided. Surface 53 and 53' is in interfering or press fitted engagement with the outside of magnet 25 in the same manner as is surface 35. The space provided by upwardly extending interior cylindrical wall 52 acts in the same manner as the space provided by wall 34 to receive portions of metal which may be forced thereinto by forcibly engaging pole piece 50 with magnet 25. Pole piece 50 or 50' may have a lower bottom edge 54 or 54' and extending upwardly from the'lower bottom edge 54 or 54' there is provided a cylindrical exterior surface 55 which is preferably identical in the embodiments of FIGURES 3 and 4 and in the assembly is spaced equidistant inwardly from the wall 36 of the cup piece to provide a cylindrically annular space of uniform width to receive the voice coil and voice coil supporting tube,

so that substantially all the flux lines of the magnet pass through the voice coil, that is, so that the voice coil intercepts or may intercept all of the lines of flux available from the magnet. The embodiment of upper surface 56' of the embodiment of FIGURE 4 may be fiat as shownin FIGURE 4 or any other desired shape. 'In the preferred embodiment of FIGURE 3, an upper exterior surface extends inwardly from the upper surface 55 to provide a flat annular surface 56 having inner periphery 57. From periphery 57, a cylindrical surface 58 extends downwardly thence inwardly and thence upwardly to provide outer cylindrical surface 59 which is shown in the embodiment of FIGURE 2 as adapted to engage a suitably disposed inner cylindrical surface 69 of rigid supporting member 70. Extending inwardly from the upper edge of surface 59 there may be provided a flat surface 60. Surface 56 may engage abuttingly the corresponding flat surface 72 of supporting member 70 to cause the axis of the assembly to be parallel with the axis of member 70. A closely fitting relation between surfaces 69 and 59 cause the assembly 20 to be located coaxially with respect to voice coil support tube 11 and voice coil 13.

Rigid supporting member 70 is made of any rigid, non-magnetic material such as copper or aluminum or a plastic such as phenolic plastic. It is preferably made of metal so that it may be attached to basket 1 by staking as shown at 75.

In the embodiment of FIGURE 3, pole piece 50 is provided with threaded hole 61 for use in the embodiment of FIGURE 2. Threading of the hole may be omitted if the pole piece is to be used only in the embodiment of FIGURE 1.

The outer surface 73 of member 70 is preferably cylindrical as shown but may be polygonal. At its lower end, member 70 is provided with a flat inwardly extending annular surface 74 to serve as a shoulder to abuttingly engage the flat upper surface of basket 1 to cause the assembly which comprises assembly 20' and member 70 to be located with its axis parallel to the axis of voice coil support tube 11 which in turn is mounted so that its axis is normal to the upper interior surface of basket 1.

From the interior edge of surface 74, a surface 76, preferably cylindrical, extends downward and is of such dimensions as to mate with periphery 3 of the hole in basket 1 so that member 70 can be attached to basket 1 by staking as shown at 75. Recess 77 may be provided in the bottom of member 70 and assembly 20 may be attached to member 70 by threaded screw 80 which may be threadedly engaged with hole 61 in pole piece 50 an may have its head received in recess 77.

In the embodiment of FIGURE 1, pole piece 50' may replace pole piece 50. In either the embodiment of FIG- URES 1 or 2, cup piece 30' may replace cup piece 30 if desired.

The recess provided in the upper surface of pole piece 50 by downwardly extending cylindrical surface 58 which thence extends inwardly, is adapted to prevent dislocation of assembly 20 With respect to member 70 by providing a reservoir to receive any portions of metal forced therein if surfaces 59 and 69 have an interfering fit such as to cause portions of metal to extend upwardly from the inner upper edge of surface 69.

It may thus be seen that the invention is broad in scope and includes such modifications as will be apparent to those skilled in the art and is to be limited only by the claims.

Having thus described my invention, I claim:

1. For use in a loud speaker, a magnet and supporting assembly comprising said magnet, a cup piece and a pole piece,

said magnet being a cylinder of permanently magnetizable material having a first end and a second end, said cup piece having a bottom which is in contact with the first end of said magnet,

a hollow substantially cylindrical side portion extending upward from said bottom portion and partially spaced away from said magnet, said i side porting having a first interior cylindrical surface portion engaged in press-fitted or interfacing relation with the outside of said magnet near the first end of said magnet, to attach the cup to the magnet, a second interior cylindrical wall surface portion having a greater diameter than said first interior surface portion to provide a space between said side portion and said magnet, a first exterior outer wall surface portion, and a second exterior wall surface portion spaced inwardly from said first exterior wall surface portion and located at the top peripheral outer edge of the side portion, said pole piece being generally cup shaped and having a laterally extending wall having an upper surface and a lower surface, said lower surface being in contact with the second end of said magnet,

a hollow substantially cylindrical side portion depending substantially from the periphery of said laterally extending wall portion, said side portion having an interior cylindrical wall surface portion engaged in press-fitted or interfering relation with the outside of said magnet near its second end to attach the pole piece to the magnet and an exterior cylindrical wall surface portion which has a diameter less than that of the second interior wall surface portion of the side portion of said cup piece to provide space between said surfaces of said pole piece and cup piece to receive a voice coil and voice coil support tube. 2. For use in a loud speaker, a magnet and supporting assembly comprising said magnet, a cup piece and a pole piece,

said magnet being a cylinder of permanently magnetizable material having a first end an a second end,

said cup piece having an interior bottom surface extending laterally to a periphery, said surface being in contact with the first end of said magnet, an interior cylindrical wall surface extending downwardly from said periphery, thence outwardly and thence upwardly into press-fitted or interfering engagement with the outside of said magnet near the first end thereof to attach the cup to the magnet and thence outwardly and thence upwardly as an upper interior cylindrical surface spaced away substantially equidistant at all points from the outer surface of said magnet, thence outwardly to provide an upper edge surface, thence downwardly as a cylindrical exterior surface to provide for engagement with the basket of a loud speaker, thence outwardly to provide a shoulder for engaging the bottom of the basket of a loud speaker, thence downwardly to provide a principal exterior surface and thence inwardly to provide a laterally extending exterior bottom surface,

said pole piece having an interior bottom surface extending laterally to a periphery, said surface being in contact with the second end of said magnet, an interior cylindrical Wall surface extending upwardly from said periphery, thence outwardly and thence downwardly into press-fitted or interfering engagement with the outside of said magnet near the second end thereof to attach the pole piece to the magnet and thence outwardly to provide a lower bottom edge,

thence upwardly as a cylindrical exterior surface spaced equidistant inwardly from the upper interior cylindrical surface of said cup piece to receive a voice coil and voice coil support tube thereinbetween and thence'inwardly to provide a laterally extending eX- terior top surface. 3. For use in a loud speaker, a magnet and supporting assembly comprising said magnet, a rigid supporting memher, a cup piece and a pole piece,

said magnet being a cylinder of permanently magnetizable material having a first end and a second end,

said cup piece having an interior bottom surface extending laterally to a periphery, said surface being in contact with the first end of said magnet, an interior cylindrical wall surface extending downwardly from said periphery, thence outwardly and thence upwardly into press-fitted or interfering engagement with the outside of said magnet near the first end thereof to attach the cup to the magnet and thence outwardly and thence upwardly as an upper interior cylindrical surface spaced away substantially equidistant at all points from the outer surface of said magnet, thence outwardly to provide an upper edge surface, thence downwardly to provide a principal exterior surface and thence inwardly to provide a laterally extending exterior bottom surface,

said pole piece having an interior bottom surface extending laterally to .a periphery, said surface being in contact with the second end of said magnet, an interior cylindrical wall surface extending upwardly from said periphery, thence outwardly and thence downwardly into press-fitted or interfering engagement with the outside of said magnet near the second end thereof to attach the pole piece to the magnet and thence outwardly to provide a lower bottom edge, thence upwardly as a cylindrical exterior surface spaced equidistant inwardly from the upper interior cylindrical surface of said cup piece to receive a voice coil and voice coil support tube thereinbetween, thence inwardly to an inner periphery to provide a laterally extending annular upper surface to provide a shoulder to receive said supporting member, an exterior surface extending downwardly from said inner periphery and thence inwardly and thence upwardly to provide a cylindrical outer surface to engage a mating surface of said supporting member for positioning the pole piece coaxially with the supporting member, thence inwardly to provide a top surface.

4. In combination with a loud speaker comprising a basket having a hole near its center and an outer periphery, a diaphragm having a hole at its center and an outer periphery, an annular flexible supporting member having an inner periphery and an outer periphery, a voice coil supporting tube and a voice coil,

the voice coil supporting tube extending vertically and having the voice coil wrapped therearound,

one end of the voice coil supporting tube and the inner periphery of the annular flexible supporting member attached to the periphery of the hole in the diaphragm,

the outer periphery of the annular flexible supporting member attached to the basket,

the outer periphery of the diaphragm attached to the outer periphery of the basket;

a magnet and supporting assembly comprising said maga first interior cylindrical surface portion engaged in press-fitted or interfacing relation with the outside of said magnet near the first end of said magnet, to attach the cup to the magnet,

a second interior cylindrical wall surface portion having a greater diameter than said first interior surface portion to provide a space between said side portion and said magnet,

a first exterior outer wall surface portion, and

a second exterior wall surface portion spaced inwardly from said first exterior Wall surface portion and located at the top peripheral outer edge of the side portion,

said second exterior Wall portion extending into the'hole in said basket and said cup piece being attached to said basket,

said pole piece being generally cup shaped and having a laterally extending wall having an upper surface and a lower surface, said lower surface being in contact with the second end of said magnet, a hollow substantially cylindrical side portion depending substantially from the periphery of said laterally extending wall portion, said side portion having an interior cylindrical Wall surface portion engaged in press-fitted or interfering relation with the outside of said magnet nearits secondend to attach the pole piece to the magnet and an exterior cylindrical wall surface portion Which has a diameter less than that of the second interior wall surface portion of said cup piece to provide space between said surfaces of said pole piece and cup piece to receive said voice coil support tube with said voice coil thereon.

5. In combination with a loud speaker comprising a basket having a hole near its center and an outer periphery, a diaphragm having a 'hole at its-center and an outer periphery, an annular'fiexible supporting member having an inner periphery and an outer periphery, a voice coil supporting tube and a voice coil,

the voice coil supporting tube extending vertically and having the voice coil wrapped therearound,

one end of the voice coil supporting tube and the inner periphery of the annular flexible supporting member attached to the periphery of the hole in the diaphragm,

the outer periphery of the annular flexible supporting member attached to the basket,

the outer periphery of the diaphragm attached to the outer periphery of the basket;

a magnet and supporting assembly comprising said magnet, a rigid supporting member, a cup piece and a pole piece,

said magnet being a cylinder of permanently mag netizable material having a first end and a second end,

said cup piece having a bottom which is in contact with the first end of said magnet,

a hollow substantially cylindrical side portion extending upward from said bottom portion and partially spaced away from said magnet, said side portion having a first interior cylindrical surface portion engaged in press-fitted or interfering relation with the outside of said magnet near the first end of said magnet, to attach the cup to the magnet,

a second interior cylindrical wall surface portion having a greater diameter than said first interior surface portion to provide a space between said side portion and said magnet, a first exterior outer wall surface portion, and a second exterior wall surface portion spaced inwardly from said first exterior wall surface portion and located at the top peripheral outer edge of the side portion, said pole piece being generally cup shaped and having a laterally extending wall having an upper surface and a lower surface, said lower surface being in contact with the second end of said magnet,

a hollow substantially cylindrical side portion depending substantially from the periphery of said laterally extending wall portion, said side portion having an interior cylindrical wall surface portion engaged in press-fitted or interfering relation with the outside of said magnet near its second end to attach the pole piece to the magnet, and an exterior cylindrical Wall surface portion which has a diameter less than that of the second interior wall surface portion of the side portion of said cup piece to provide space between said surfaces of said pole piece and cup piece to receive said voice coil support tube with said coilthereon, said rigid supporting member engaged at one end with said pole piece and at the other end with said hole in said basket, to hold said magnet and supporting assembly invertedly over said diaphragm. A 6. In combination with'a loud speaker comprising a basket having a hole near its center and an outer periphery, a diaphragm having a hole at its center and an outer periphery, an annular flexible supporting member having an inner periphery and an outer periphery, a voice coil supporting tube and a voice coil,

the voice coil supporting tube extending vertically and having the voice coil wrapped therearound,

one end of the voice coil supporting tube and the inner periphery of the annular flexible supporting member attached to the periphery of the hole in the diaphragm,

the outer periphery of the annular flexible supporting member attached to the basket,

the outer periphery of the diaphragm attached to the outer periphery of the basket;

a magnet and supporting assembly comprising said magnet, a cup piece and a pole piece,

said magnet being a cylinder of permanently magnetiz able material having a first end and a second end,

said cup piece having an interior bottom surface extending laterally to a periphery, said surface being in contact with the first end of said magnet, an interior cylindrical wall surface extending downwardly from said periphery, thence outwardly and thence upwardly into press-fitted or interfering engagement with the outside of said magnet near the first end thereof to attach the cup to the magnet and thence outwardly and thence upwardly as an upper interior cylindrical surface spaced away substantially equidistant at all points from the outer surface of said magnet, thence outwardly to provide an upper edge surface, thence downwardly as a cylindrical exterior surface which extends into the hole in the basket, thence outwardly to provide a shoulder which engages the bottom of the basket of a loud speaker, th'ence downwardly to provide a principal exterior surface and thence in- I wardly to provide a laterally extending exterior bottom surface, 7 said pole piece having an interior bottom surface extending laterally to a periphery, said surface being in con tact with the second end of said magnet, an interior cylindrical wall surface extending upwardly from said periphery, thence outwardly and thence downwardly into press-fitted or interfering engagement with the outside of said magnet near the second end thereof to attach the pole piece to the magnet and thence outwardly to provide a lower bottom edge, thence upwardly as a cylindrical exterior surface spaced equidistant inwardly from the upper interior cylindrical surface of said cup piece to receive a voice coil and voice coil support tube thereinbetween.

7. In combination with a loud speaker comprising a basket having a hole near its center and an outer periphery, a diaphragm having a hole at its center and an outer periphery, an annular flexible supporting member having an inner periphery and an outer periphery, a voice coil supporting tube and a voice coil,

the voice coil supporting tube extending vertically and having the voice coil wrapped therearound,

one end of the voice coil supporting tube and the inner periphery of the annular flexible supporting member attached to the eriphery of the hole in the diaphragm,

the outer periphery of the annular flexible supporting member attached to the basket,

the outer periphery of the diaphragm attached to the outer periphery of the basket;

a magnet and supporting assembly comprising said ma net, a rigid supporting member, a cup piece and a pole piece,

said magnet being a cylinder of permanently magnetizable material having a first end and a second end,

said cup piece having an interior bottom surface extending laterally to a periphery, said surface being in contact with the first end of said magnet, an interior cylindrical wall extending downwardly from said periphery, thence outwardly and thence upwardly into press fitted or interfering engagement with the outside of said magnet near the first end thereof to attach the cup to the magnet and thence outwardly and thence upwardly as an upper interior cylindrical surface spaced away substantially equidistant at all points from the outer surface of said magnet, thence outwardly to provide an upper edge surface, thence downwardly to provide an exterior surface and thence inwardly to provide a laterally extending exterior bottom surface, said pole piece having an interior bottom surface extending laterally to a periphery, said surface being in contact wtih the second end of said magnet, an interior cylindrical wall surface extending upwardly from said periphery, thence outwardly and thence dovtmwardly into press-fitted or interfering engagement with the outside of said magnet near the second end thereof to attach the pole piece to the magnet and thence outwardly to provide a lower bottom edge, thence upwardly as a cylindrical exterior surface spaced equidistant inwardly from the upper interior cylindrical surface of said cup piece to receive a voice coil and voice coil support tube thereinbetween, thence inwardly to an inner periphery to provide a laterally extending annular upper surface to provide a shoulder to receive said supporting member, an exterior cylindrical surface extending downwardly from said inner periphery and thence inwardly and thence upwardly to provide a cylindrical outer surface to engage a mating surface of rigid supporting member for positioning the pole piece co-axially with the rigid supporting member, thence inwardly to provide a top surface,

the rigid supporting member extending at one end into the hole in said basket and attached to said basket and said pole piece, to hold said magnet and supporting assembly invertedly over said diaphragm.

No references cited.

ROBERT H. ROSE, Primary Examiner.

F. N. CARTEN, Assistant Examiner. 

1. FOR USE IN A LOUD SPEAKER, A MAGNET AND SUPPORTING ASSEMBLY COMPRISING SAID MAGNET, A CUP PIECE AND A POLE PIECE, SAID MAGNET BEING A CYLINDER OF PERMANENTLY MAGNETIZABLE MATERIAL HAVING A FIRST END AND A SECOND END, SAID CUP PIECE HAVING A BOTTOM WHICH IS IN CONTACT WITH THE FIRST END OF SAID MAGNET, A HOLLOW SUBSTANTIALLY CYLINDRICAL SIDE PORTION EXTENDING UPWARD FROM SAID BOTTOM PORTION AND PARTIALLY SPACED AWAY FROM SAID MAGNET, SAID SIDE PORTING HAVING A FIRST INTERIOR CYLINDRICAL SURFACE PORTION ENGAGED IN PRESS-FITTED OR INTERFACING RELATION WITH THE OUTSIDE OF SAID MAGNET NEAR THE FIRST END OF SAID MAGNET, TO ATTACH THE CUP TO THE MAGNET, A SECOND INTERIOR CYLINDRICAL WALL SURFACE PORTION HAVING A GREATER DIAMETER THAN SAID FIRST INTERIOR SURFACE PORTION TO PROVIDE A SPACE BETWEEN SAID SIDE PORTION AND SAID MAGNET, A FIRST EXTERIOR OUTER WALL SURFACE PORTION, AND A SECOND EXTERIOR WALL SURFACE PORTION SPACED INWARDLY FROM SAID FIRST EXTERIOR WALL SURFACE PORTION AND LOCATED AT THE TOP PERIPHERAL OUTER EDGE OF THE SIDE PORTION, SAID POLE PIECE BEING GENERALLY CUP SHAPED AND HAVING A LATERALLY EXTENDING WALL HAVING AN UPPER SURFACE AND A LOWER SURFACE, SADI LOWER SURFACE BEING IN CONTACT WITH THE SECOND END OF SAID MAGNET, A HOLLOW SUBSTANTIALLY CYLINDRICAL SIDE PORTION DEPENDING SUBSTANTIALLY FROM THE PERIPHERY OF SAID LATERALLY EXTENDING WALL PORTION, SAID SIDE PORTION HAVING AN INTERIOR CYLINDRICAL WALL SURFACE PORTION ENGAGED IN PRESS-FITTED OR INTEFERING RELATION WITH THE OUTSIDE OF SAID MAGNET NEAR ITS SECOND END TO ATTACH THE POLE PIECE TO THE MAGNET AND AN EXTERIOR CYLINDRICAL WALL SURFACE PORTION WHICH HAS A DIAMETER LESS THAN THAT OF THE SECOND INTERIOR WALL SURFACE PORTION OF THE SIDE PORTION OF SAID CUP PIECE TO PROVIDE SPACE BETWEEN SAID SURFACES TO SAID POLE PIECE AND CUP PIECE TO RECEIVE A VOICE COIL AND VOICE COIL SUPPORT TUBE. 